Rubric Introduces an Attestation System for AI Agent Decisions

Summary

Rubric describes a decision-attestation system designed to make recording AI agent decisions free while charging $0.10 for each verification. Its default records contain only SHA3-256 hashes over JCS-canonicalized data, so the decision payload stays on the client unless the optional payload mode is used. Records are chained per agent, include Merkle proofs, use threshold signatures from ML-DSA-65 keys across regions, and are anchored to Hedera mainnet minutes after a decision; the system says an anchored record cannot be backdated or revised, including by Rubric. Verification is exposed through an x402 machine-to-machine endpoint that requires no account and checks bundle consistency, Merkle proofs, signatures, and DAR versioning. The repository is an npm-workspaces monorepo containing the DAR/0.1 specification, an attestation SDK, a SQLite-based index, adapters for Jev and JSON Schema/Zod, a verification route, and an evidence-bundle export CLI. The SDK returns immediately, spools records durably, batches up to 64 records or 5,000 milliseconds, and provides at-least-once delivery; callers must de-duplicate retries by decisionId. The documentation also describes limits: a disk failure can prevent spooling, outages can trigger a 50 MB drop-oldest spool cap, and multiple producers for one agent can create independent branches rather than a single global sequence. The current signing federation has three regions operated by Rubric, so its threshold protects against key compromise but not against Rubric as an institution. The verification route checks internal cryptographic consistency but does not itself confirm the Hedera anchor or trust the signing key; the documented anchor-linking procedure is separate.